Power lift



Aug. 7, 1951 F. w. WELLS ET AL 2,553,143

POWER LIFT Original Filed Feb. 27, 1942 I IN VEN TORS. M05557? r/ruu/ z/y iigmwflmw Patented Aug. 7, 1951 Kulhavy; Rock Island, Ill, assignors to J. I. Case Company, Racine, Wis., a corporation of Wisconsin Original application February 27,1942} Serial No. 432,670. Divided and thisv application October 4, 1947, Serial No. 777,993

5 Claims. (01. 74- 104) The present invention relates to power lift apparatus andparticularly to'such'apparatus as is adapted for application to tractors. This'application is a division of a co-pending application, Serial No. 432,670, filed Feb. 27, 1942, and allowed April 9, 1947, now Patent No. 2,430,197.

An object of the invention is to generally improve the construction and operation of devices of this class. More particularly the'invention' relates to power lifts having arms which are actu-' ated by fluid pressure and a further object of the invention is to avoid-binding and excessive friction and wear in such rams and connected parts thereof.

A further object of the invention is to provide expedients-for the accomplishment of the novel objects.

Further objects and advantages of the invention will become apparent" from a consideration of the following detailed description taken in connection with the accompanying drawing wherein a satisfactory embodiment? of the invention is shown. However, it is to be understood that the invention is notlimited to the'details disclosed but includes all such variations and modifications as fall within the spirit of the invention as herein expressed. In the annexed drawing,

The single'figure. is a vertical sectional View of an illustrative embodiment of the invention.

As seen in the drawing. the invention comprises a casing or housing'5 which may be bolted or otherwise fixed on a tractor (not shown) in any convenient location to become a part thereof. Housing 5 serves to enclose the mechanism of the power lift proper and also as-a reservoir forfiuid. A shaft 5 which may be, for example, a power take-off shaft extending from the" tractor in any convenient or well-known location, traverses housing 5' and is supported therein in anti-friction or other suitable bearings, it being desirable to locate housing 5 at such a point on the tractor that one of the well-known externally projecting power shafts commonly provided will pass through the housing 5 to serve as shaft 6. Shaft 6 actuates a pump unit generally designated as 9 which forces fluid from reservoir 5, when desired, into a ram cylinder I for accomplishingthe usual purpose of a power lift, the fluid returning to reservoir through an outlet valvegenerall'y designated as II when it is desired to lower the implements or objects connected with the lift. In the event that excessive pressure is developed for any reason by the action of pump 9, this is relieved by a relief valve generally designated as I2 and control means generally designated as I3 operate to start and stop the actuation of pump 9- by shaft 6 and also to actuate outlet valve iI, control means I3 being adapted to automatically return to a neutral position whenever released, "whereupon pump 9- stops and any'implement connected with the power lift remains in statusquo.

Ram cylinder I0 has a pistontherein generally designat'edas I 00 having a rod Ilii extending upwardly through a suitable oil retainerof any wellknown type I02; Ahead I-fl3isfixed to rod- IOI and extends to one side where it is fixed with a guide rod I06, slidable in a guide portion I05 in the present instance forming part of housing 5; In this manner piston I00 is definitelyguided independently of cylinder I0 so that any side thrust reaction occasioned by implements connected to be lifted or the like is taken by'guide rod I0 3 rather than thewa-lls of cylinder I0. Undue wear of the cylinder is thereby eliminated.

To minimize suchside thrust, a connection to elements to be lifted is provided in the present instance inthe form of a rock shaft I06 journaled in a suitable hearing or support III! fixed with the tractor. Any well-known connection from rock shaft I06 to the various implements 1 which it is desired to lift may be provided as will readily be understood by one skilled in the art. Rock shaft lllli has a bifurcated arm I08 extending to a region above piston rod I0! atwhich point i'tis pivotally connected with'a thrust block I 59 by a pin or the like I I0. Thrust block I09 is pivotally connected as by a pin I I I with a bifurcated or-suitable guide arm H2 pivoted at III! the present instance to above mentioned bearing I07. Thrust block Ills has a face H4 preferably at right angles to piston rod IIlI andheadxlfl3 is provided with anfia'ntifriction" abutment, for example, a rollerl I5 in contact with face I It.

Inthe present arrangement, pivots III] and I II are disposed in a plane parallel to rod IOI. Rock shaft'l flfi and pivot H3 are also disposed in a plane parallel to shaft IOI, arm I08, and. guide arm II2 being of equal length. Consequently, during swinging movement of arm I08 and guide arm I'I2,, block I09 will in all positions remain parallel torod IIJI. Therefore, since face H4 is at substantially right angles to rod IN, the reaction on rod IGI will always be axial to the rod and no side thrust will be developed by the rod IOI against block I09. Any side thrust developed by friction roller I I5 is taken up by guide rod I 04. Other arrangements which will insure that face H4 will remain perpendicular to rod I0! are 3 contemplated as within the scope of the invention.

Cylinder I may be secured in housing 5 in any suitable or desired manner, in the present instance the cylinder being seated against a gasket I38 in a counter-bore I39 by means of a nut I40 threaded in a boss I4I in housing 5. Nut I40 carries above mentioned oil retainer I02 and preferably has a bore I42 for receiving the upper end of cylinder I0. Cylinder I9 has a notch or opening I43 communicating with a clearance I44 provided in bore I42 for communication of the space above piston I90 with the interior of housing 5. This relieves any pressure or partial vacuum which might otherwise form above piston I00.

The above being a complete description of an illustrative embodiment of the invention, what is claimed as new and desired to be secured by Letters Patent of the United States is:

1. A hydraulic power lift for a tractor having a support fixed thereon' and an implement lifting rockshaft rockably carried by the support, said power lift including a housing and a ram associated therewith and including a piston rod guided for reciprocatory movement in said housing, an oscillatable actuating arm fixed to said rockshaft, extending therefrom and terminating adjacent said piston rod to receive oscillating motion therefrom, a link pivotally supported on the tractor, spaced from said arm in the direction of motion of said piston rod and coextensive with and parallel to said arm, a thrust block pivoted to and carried by said arm and said link in position to receive thrust from said piston rod for oscillating said arm, and friction minimizing contact means between said piston rod and said thrust block.

2. A hydraulic power lift for a tractor having a support fixed thereon and an implement lifting rockshaft rockably carried by the support, said power lift including a housing, a ram reciprocable in said housing and including a piston rod, a guide rod having an axis parallel to the axis of said piston rod and slidably associated with said housing, a head member rigidly secured to said piston rod and to said guide rod so as to resist the transmission of lateral forces to said piston rod, an oscillatable actuating arm fixed to saidrockshaft extending therefrom and terminating adjacent said piston rod to receive oscillating motion therefrom, a link pivotally supported on the tractor, spaced from said arm in the direc-- tion of motion of said piston rod, coextensive with and parallel to said arm, a thrust block pivoted to and carried by said arm and said link in position to receive thrust from said piston rod by engagement with said head member for oscillating said arm, and friction minimizing contact means between said thrust block and said head member.

3. A hydraulic power lift for a tractor having a support fixed thereon and an implement lifting rockshaft rockably carried by the support, said powerlift including a housing, a ram reciprocable in said housing and including a piston rod, a guide rod having an axis parallel to the axis of said piston rod and slidably associated with-said housing, a head member rigidly secured to said piston rod and to said guide rod so as to resist the transmission of lateral forces to said piston rod, an oscillatable actuating arm fixed to said rockshaft extending therefrom and terminat- 4 ing adjacent said piston rod to receive oscillating motion therefrom, a link pivotally supported on the tractor, spaced from said arm in the direction of motion of said piston rod, coextensive with and parallel to said arm, a thrust block pivoted to and carried by said arm and said link in position to receive thrust from said piston rod by engagement with said head member for oscillating said a support fixed thereon and an implement lifting rockshaft rockably carried by the support, said power lift including a housing, a ram reciprocable in said housing and including a piston rod, a guide rod having an axis parallel to the axis of said piston rod displaced therefrom in a plane normal to said rockshaft and slidably associated with said housing, a head member rigidly secured to said piston rod and to said "guide rod so as to resist the transmission of lateral forces to said piston rod, an oscillatable actuating arm fixed to said rockshaft extending therefrom and terminating adjacent said piston rod to receive oscillating motion therefrom, a link pivotally supported on the tractor, spaced from said arm in the direction of motion of said piston rod, coextensive with and parallel to said arm, a thrust block pivoted to and carried by said arm and said link in position to receive thrust from said piston rod by engagement with said head member for oscillating said arm, and friction minimizing contact means between said thrust block and said head member.

5. In a hydraulic power lift for a tractor the combination of a housing mounted on the tractor,

a ram associated 'with the housing and including a piston rod guided for reciprocating movement in said housing, a support fixed on the tractor, an implement lifting rockshaft rockably carried by the support, an arm fixed to said roekshaft, extending therefrom and terminating adjacent said piston rod to receive oscillating motion therefrom, a link pivotally carried by said support, spaced from said arm in the direction of motion of said piston rod and co-extensive with and parallel to said arm, a thrust block pivoted to and carried by said arm and said link in position to receive thrust from said piston rod for oscillating said arm, and friction minimizing contact means between said piston rod and said thrust block.

FRANK W. WELLS.

JOSEPH T. KULHAVY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

